<meta charset="utf-8">
(#) Application uses vulnerable cryptography algorithms

!!! ERROR: Application uses vulnerable cryptography algorithms
   This is an error.

Id
:   `VulnerableCryptoAlgorithm`
Summary
:   Application uses vulnerable cryptography algorithms
Severity
:   Error
Category
:   Security
Platform
:   Any
Vendor
:   Google - Android 3P Vulnerability Research
Contact
:   https://github.com/google/android-security-lints
Feedback
:   https://github.com/google/android-security-lints/issues
Min
:   Lint 4.1
Compiled
:   Lint 8.0 and 8.1
Artifact
:   [com.android.security.lint:lint](com_android_security_lint_lint.md.html)
Since
:   1.0.1
Affects
:   Kotlin and Java files
Editing
:   This check runs on the fly in the IDE editor
See
:   https://goo.gle/VulnerableCryptoAlgorithm
Implementation
:   [Source Code](https://github.com/google/android-security-lints/tree/main/checks/src/main/java/com/example/lint/checks/BadCryptographyUsageDetector.kt)
Tests
:   [Source Code](https://github.com/google/android-security-lints/tree/main/checks/src/test/java/com/example/lint/checks/BadCryptographyUsageDetectorTest.kt)
Copyright Year
:   2023

Using weak or broken cryptographic hash functions may allow an attacker
to reasonably determine the original input or produce multiple inputs
with the same hash value.

!!! Tip
   This lint check has an associated quickfix available in the IDE.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/fake/pkg/TestBadCryptoDetector.java:8:Error: Using vulnerable
cryptographic algorithms puts the original input at risk of discovery
[VulnerableCryptoAlgorithm]
    Cipher.getInstance(algo);
    ------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`src/fake/pkg/TestBadCryptoDetector.java`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers
package fake.pkg;

import javax.crypto.Cipher;

public class TestBadCryptoDetector {
    private void foo() {
        String algo = "RC2";
        Cipher.getInstance(algo);
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://github.com/google/android-security-lints/tree/main/checks/src/test/java/com/example/lint/checks/BadCryptographyUsageDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `BadCryptographyUsageDetector.testWhenVulnerableCryptoBlockAlgoUsed_showsErrorAndQuickFix`.
To report a problem with this extracted sample, visit
https://github.com/google/android-security-lints/issues.

(##) Including

!!!
   This is not a built-in check. To include it, add the below dependency
   to your project. This lint check is included in the lint documentation,
   but the Android team may or may not agree with its recommendations.

```
// build.gradle.kts
lintChecks("com.android.security.lint:lint:1.0.3")

// build.gradle
lintChecks 'com.android.security.lint:lint:1.0.3'

// build.gradle.kts with version catalogs:
lintChecks(libs.com.android.security.lint.lint)

# libs.versions.toml
[versions]
com-android-security-lint-lint = "1.0.3"
[libraries]
# For clarity and text wrapping purposes the following declaration is
# shown split up across lines, but in TOML it needs to be on a single
# line (see https://github.com/toml-lang/toml/issues/516) so adjust
# when pasting into libs.versions.toml:
com-android-security-lint-lint = {
    module = "com.android.security.lint:lint",
    version.ref = "com-android-security-lint-lint"
}
```

1.0.3 is the version this documentation was generated from;
there may be newer versions available.

[Additional details about com.android.security.lint:lint](com_android_security_lint_lint.md.html).
(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("VulnerableCryptoAlgorithm")
  fun method() {
     getInstance(...)
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("VulnerableCryptoAlgorithm")
  void method() {
     getInstance(...);
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection VulnerableCryptoAlgorithm
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="VulnerableCryptoAlgorithm" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'VulnerableCryptoAlgorithm'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore VulnerableCryptoAlgorithm ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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